Coolant Leak - Makes No Sense!

[thepaul500]

Ok, Im stumped and so is the shop I took it in, let me try and give as much info as possible. I thought I was smart until this problem hit (First time post here, btw, tons of info!!!!) Truck has 162,000 miles, not sure of its full history.

 

Left truck sitting for too long, now it leaks coolant everywhere. So, I replace the fitting into the intake manifold, corrected that leak. Replaced upper/lower manifold gasket, fixed those leaks.

 

So, fill it up with coolant, and it leaks out a fairly steady stream what seems like out of the starter. Pull the starter, and I cannot trace the leak for the life of me before it stops. Once it drains down the resevoir a bit, it goes away.

 

So, I put the system under pressure, and no leaks over 45 minutes. Fill it back up, and it drains down again, same place, then stops once it hits a certain level.

 

Any ideas, help, thoughts jokes????????? Winter is fast approaching and the Mustang doesn't do well in the snow...Thanks in advance.

[8.1HD/ALLISON]

Im guessing you either have a core plug leaking, or the intake manifold did not seal up in the back corner and is leaking.

[thepaul500]

Im guessing you either have a core plug leaking, or the intake manifold did not seal up in the back corner and is leaking.

 

If by core plug you mean freeze plug, isnt leaking. Intake manifold isn't leaking either, it looks dry all the way around. It seriously held pressure for 45 minutes and didn't leak any coolant.

 

Could it be a cracked block (hairline crack that I just cant see somewhere?)

 

The shop was saying they could try replacing the head gaskets, but would have no idea if it would fix it. I want them to do a compression test, but all the plugs were clean so I doubt thats the leak.

[txab]

You can add dye to the coolant to help trace the leak

[wavery]

Sounds to me like someone put something in your cooling system that shouldn't oughta be there....

 

All those leaks didn't just happen at once for no reason unless there was only water in the engine and it froze solid. In that case........ ya, cracked block should be considered.

[thepaul500]

Sounds to me like someone put something in your cooling system that shouldn't oughta be there....

 

All those leaks didn't just happen at once for no reason unless there was only water in the engine and it froze solid. In that case........ ya, cracked block should be considered.

 

First, the coolant being orange makes it fairly easy to spot leaks I feel...except for this one.

 

I didn;t put anything in, it was more that I used to park on gravel and didn't care how much it leaked. Top off's are cheap and none ever turned into internal leak, so I let them be. Long story short, bought a house, and the driveway was looking horrible after a day (Im sure the neighbors animals are very happy im getting it fixed too). Im a horrible person for not doing it sooner, but better late then never?

 

Cracked block doesn't explain why it doesn't leak under pressure, but only when filled all the way to the top? It should leak when the system is pressurized, no?

[govtech]

i cant get over the fact that looking hard with a light as it streams out you cant find it ,,,,,

[thepaul500]

i cant get over the fact that looking hard with a light as it streams out you cant find it ,,,,,

 

You're telling me, I feel like an idiot. I would never take something this old to a shop unless I was dumbfounded. Even the mechanics at the shop can't find the darn thing (and I thought these guys were good...)

 

Step 1: Remove starter.

Step 2: Fill up reservoir.

Step 3: Use xenon flashlight to trace, get covered in antifreeze.

Step 4: Don't find the leak, go online, look like an idiot because you cant find it.

Step 5: Wish for a miracle??

 

I don;t want to just start wholesale replacing things till I get a better idea of where to look. I was hoping someone else had had this problem before.

[00Silverado4x4]

I don't recall your engine bay set up but is it possible your overflow is cracked? That would explain a lot of your symptoms. Just a thought. Take it, toss it, hope you find the leak.

[wavery]

It's possible that a leaking head gasket could seal up under pressure or when warm. When the engine cools or pressure off, the gasket could open up. I haven't experienced it but it is theoretically possible.

 

I've never opened up a 5.3, so I may be talking out of my ass here but it seems plausible...... BTW..... I suppose a cracked block could do the same. If the crack is next to a boss in the casting, it could close the crack under pressure, then the crack could open again when the pressure is off.

 

Sounds like you need a good cooling system die and add a small amount at a time.

[Mizz]

sounds like your overflow tank may be cracked. maybe the coolant is running down a hose then dripping off by the starter? good luck